The present invention relates to the discovery of compositions which include fluoroethane, 2-fluoropropane or tert-butylfluoride. These compositions are useful as pure components or with at least one of tetrafluoroethane, difluoroethane, hexafluoropropane, a hydrocarbon or dimethylether.
These compositions are useful as aerosol propellants, refrigerants, cleaning agents, expansion agents for polyolefins and polyurethanes, refrigerants, heat transfer media, gaseous dielectrics, fire extinguishing agents, power cycle working fluids, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, and displacement drying agents.
Fluorinated hydrocarbons have had many uses, such as aerosol propellants, blowing agents and refrigerants. These compounds include trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and chlorodifluoromethane (HCFC-22).
In recent years it has been pointed out that certain kinds of fluorinated hydrocarbons released into the atmosphere may adversely affect the stratospheric ozone layer. Although this proposition has not yet been completely established, there is a movement toward the control of the use and the production of certain chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) under an international agreement.
There is also a demand for aerosol propellants and blowing agents which have significantly less photochemical reactivity than hydrocarbons that contribute to the formation of ambient ozone and ground level smog. These compounds are typically referred to as low-VOC (volatile organic compound) or non-VOC.
Accordingly, there is a demand for the development of refrigerants that have a lower ozone depletion potential than existing refrigerants while still achieving an acceptable performance in refrigeration applications. Hydrofluorocarbons (HFCs) have been suggested as replacements for CFCs and HCFCs since HFCs have no chlorine and therefore have zero ozone depletion potential.
In refrigeration applications, a refrigerant is often lost during operation through leaks in shaft seals, hose connections, soldered joints and broken lines. In addition, the refrigerant may be released to the atmosphere during maintenance procedures on refrigeration equipment. If the refrigerant is not a pure component or an azeotropic or azeotrope-like composition, the refrigerant composition may change when leaked or discharged to the atmosphere from the refrigeration equipment. The change in refrigerant composition may cause the refrigerant to become flammable or to have poor refrigeration performance.
Accordingly, it is desirable to use as a refrigerant a single fluorinated hydrocarbon or an azeotropic or azeotrope-like composition that includes one or more fluorinated hydrocarbons.
Fluorinated hydrocarbons which are classified as low or non-VOC are also useful as aerosol propellants or blowing agents because they do not contribute significantly to ground level pollution.
Fluorinated hydrocarbons may also be used as cleaning agents or solvent to clean, for example, electronic circuit boards. It is desirable that the cleaning agents be azeotropic or azeotrope-like because in vapor degreasing operations the cleaning agent is generally redistilled and reused for final rinse cleaning.
Azeotropic or azeotrope-like compositions that include a fluorinated hydrocarbon are also useful as blowing agents in the manufacture of closed-cell polyurethane, phenolic and thermoplastic foams, as heat transfer media, gaseous dielectrics, fire extinguishing agents or power cycle working fluids such as for heat pumps. These compositions may also be used as inert media for polymerization reactions, fluids for removing particulates from metal surfaces, as carrier fluids that may be used, for example, to place a fine film of lubricant on metal parts or as buffing abrasive agents to remove buffing abrasive compounds from polished surfaces such as metal. They are also used as displacement drying agents for removing water, such as from jewelry or metal parts, as resist developers in conventional circuit manufacturing techniques including chlorine-type developing agents, or as strippers for photoresists when used with, for example, a chlorohydrocarbon such as 1,1,1-trichloroethane or trichloroethylene.
The present invention relates to the discovery of compositions which include fluoroethane, 2-fluoropropane or tert-butylfluoride. These compositions have zero ozone depletion potential (ODP), low global warming potential and are lower VOC than hydrocarbons. These compositions are also useful as pure components or with at least one of tetrafluoroethane, difluoroethane, hexafluoropropane, a hydrocarbon or dimethylether. These compositions are used as aerosol propellants, refrigerants, cleaning agents, expansion agents for polyolefins and polyurethanes, heat transfer media, gaseous dielectrics, fire extinguishing agents, power cycle working fluids, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, and displacement drying agents.
Further, the invention relates to the discovery of binary azeotropic or azeotrope-like compositions comprising effective amounts of fluoroethane, 2-fluoropropane or tert-butylfluoride and a second component of tetrafluoroethane, difluoroethane, hexafluoropropane, a hydrocarbon or dimethylether, to form an azeotropic or azeotrope-like composition. Azeotropes are highly desirable for refrigerants but not necessary for aerosol propellants.
The compounds of the present invention include the following components:
1. fluoroethane (HFC-161, or CH3CH2F, boiling point=xe2x88x9238xc2x0 C.),
2. 1,1,2,2-tetrafluoroethane (HFC-134, or CHF2CHF2, boiling point=xe2x88x9220xc2x0 C.),
3. 1,1,1,2-tetrafluoroethane (HFC-134a, or CF3CH2F, boiling point=xe2x88x9226xc2x0 C.),
4. 1,1-difluoroethane (HFC-152a, or CH3CHF2, boiling point=xe2x88x9225xc2x0 C.),
5. 2-fluoropropane (HFC-281ea, or CH3CHFCH3, boiling point=xe2x88x9211xc2x0 C.),
6. tert-butylfluoride (HFC-3-10-1sy, or (CH3)3CF, boiling point=12xc2x0 C.),
7. 1,1,1,2,3,3-hexafluoropropane (HFC-236ea, or CF3CHFCHF2, boiling point=6xc2x0 C.),
8. 1,1,1,3,3,3-hexafluoropropane (HFC-236fa, or CF3CH2CF3, boiling point=xe2x88x921xc2x0 C.),
9. dimethylether (DME, or CH3OCH3, boiling point=xe2x88x9225xc2x0 C.),
10. butane (CH3CH2CH2CH3, boiling point=xe2x88x920.5xc2x0 C.),
11. isobutane ((CH3)3CH, boiling point=xe2x88x9212xc2x0 C.),
12. propane (CH3CH2CH3, boiling point=xe2x88x9242xc2x0 C.).
HFC-161 (CAS Reg. No. 353-36-6) and HFC-281ea (isopropyl fluoride, CAS Reg. No. 420-26-8) have been prepared by reaction of hydrogen fluoride with ethylene and propylene, respectively, as reported by Grosse and Lin in J. Org. Chem., Vol. 3, pp. 26-32 (1938).
2-Fluoro-2-methylpropane (t-butyl fluoride, HFC-3-10-1y, CAS Reg. No. [353-61-7]) may be prepared by the reaction of t-butyl alcohol with aqueous hydrogen fluoride as discussed on page 689 of xe2x80x9cChemistry of Organic Fluorine Compoundsxe2x80x9d by Milos Hudlicky, 2nd. ed., 1976.